On chemical changes in their relation to micro-organisms / E. Frankland.

  • Frankland, Edward, 1825-1899.
Date:
1885
Catalogue details

Licence: Public Domain Mark

Credit: On chemical changes in their relation to micro-organisms / E. Frankland. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    18/28 (page 174)
    Bell and Fitz, however, describe a true butyric ferment which, according to the first named, consists of very active bacteria; hut, according to the second, of round cells (arranged in garlands) 1'6 to 1'7 microms. in diameter. It is obtained by adding cow’s excrement to calcic lactate. In a few days, the lactate is transformed almost entirely into normal butyrate, with traces only of acetic, caproic, and succinic acids. This is said to be the best ferment for butyric acid. I have sometimes obtained quite as good a result with cheese; but, on other occasions, a mixture of acids was produced from which it was difficult to extract any pure butyric acid. Van Tieghem finds that Bacillus amylohacter always produces butyric acid, carbonic anhydride, and hydrogen, no matter what sub- stance it operates upon. Thus, for instance, it always yields these products when it attacks cellulose, dextrin, arabin, lichenin, lactose, mannite, glycerin, calcic malate, or calcic citrate. On the other hand, when a small long bacillus, often in long bent chains, gains the victory, calcic lactate is converted into the calcium salts of propionic and acetic acids, according to the following equation:— o / CMeHHo 1 COHo Lactic acid. r CMeHj I COHo + Propionic acid. {cOHo +CO,+OH. Acetic acid. Glycerin Fermentation. Butyl bacillus and Ethyl bacillus. Fitz has observed that there is a micro-organism which converts glycerin into normal butyl alcohol, normal butryic acid, caproic acid, and a small quantity of ethyl alcohol. The acids must be continuously saturated with calcic carbonate. A good result was obtained with the following mixture :—2000 parts of water, 100 of glycerin, 1 of potassic phosphate, 0'5 of magnesic sulphate, 2 parts of pepsin (as food for the ferment), and 20 parts of chalk. To this, a trace of the ferment was added, and the mixture exposed to a temperature of 40° C. The